1. Field of the Invention
This invention relates to transmission of information in a multiple-antenna communication system, especially relates to a technology of transmission and detection for a multiple-antenna signal.
2. Description of the Related Art
With limited spectrum resources, data transmission rate can be improved effectively by using the multiple-antenna space multiplexing BLAST technology.
The existing BLAST detection algorithm may be divided to linear detection (including Zero-Forcing detection (ZF), Minimum Mean Square Error Detection (MMSE) . . . ) and nonlinear detection (including Zero-Forcing and signal Interference Cancellation detection (ZF-SIC), Minimum mean Square Error and signal Interference Cancellation detection (MMSE-SIC) . . . ).
The linear detection method is easy to be realized relatively, while with poor performance. Compared with the linear detection method, the nonlinear detection method may improve the performance of the system. However the significantly increased complexity caused by iterative interference cancellation is the main difficulty for the nonlinear detection to be put into practice.
The following is a simple outline of linear and nonlinear BLAST detection algorithm.
Linear Detection Algorithm
Assuming the received signal isr=Hs+n, 
where, H is a N×M Channel Matrix, s is an M-dimensional transmission signal vector, r is a N-dimensional receipt signal vector, n is a N-dimensional independent white Gaussian noise, M and N are the numbers of system transmitting and receiving antennas.
For Zero-Forcing detection algorithm,ŝZF=(HHH)−1HHr=s+(HHH)−1HHn. 
For MMSE (Minimum mean square error detection) algorithm,ŝMMSE=(HHH+σ2I)−1HHr=s+(HHH+σ2I)−1HHn. 
where, ŝZF and ŝMMSE are M-dimensional vectors of detected signals under different algorithms respectively.
Nonlinear Detection Algorithm
Compared with the linear detection, the nonlinear detection technology may improve the system performance effectively at the price of increase of operation complexity.
The following gives an outline of sequential interference cancellation algorithm in the BLAST nonlinear detection algorithm. The basic principle of this algorithm is to remove the interference coming from the detected parts in the process of detecting the current signals, so as to reduce the impact that interference has on data with smaller signal-to-noise ratio. This principle is similar to the decision feedback equalization.
The following describes the detection process:
For ZF-SIC detector, it will defines thatGi=H†=(HHH)−1HH,
For MMSE-SIC detector, it will defines thatGi=H†=(HHH+σI)−1HH.
After Process 1, a decision signal may be obtained:ki=argmin∥(Gi)j∥2wki=(Gi)kiyki=wkiTriâki=Q(yki)  Process 1
In the above process, k1, k2, . . . , kM form a sequence of transmitting antennas in the detection process.
Then, Process 2 is performed and the impact of the detected signals has been removed from the received signals. The new pseudo inverse matrix is determined and the new decision sequence is also determined.
                                                                        r                                  i                  +                  1                                            =                            ⁢                                                                    r                    i                                    -                                                                                                              a                          ^                                                                          k                          i                                                                    ⁡                                              (                        H                        )                                                                                    k                      i                                                                      ⇒                                  G                                      i                    +                    1                                                                                                                          =                            ⁢                                                H                                      i                    +                    1                                    †                                ⇒                                  k                                      i                    +                    1                                                                                                                          =                            ⁢                                                                    argmin                                          j                      ∉                                              {                                                                              k                            1                                                    ⁢                                                                                                          ⁢                          …                          ⁢                                                                                                          ⁢                                                      k                            i                                                                          }                                                                              ⁢                                                                                                                                    (                                                      G                                                          i                              +                              1                                                                                )                                                j                                                                                    2                                                  ⇒                i                ←                                  i                  +                  1                                                                                        Process        ⁢                                  ⁢        2            
Then a cyclical process is formed, and the cyclical process includes Process 1 and Process 2, the cyclical process is carrying out on the signals until i=M. Now, all signals have been determined, and the cyclical process is completed.
The BLAST linear detection method is easy to be realized relatively, while with poor performance. Compared with the linear detection method, the nonlinear detection method can improve the performance of the system. However the significantly increased complexity caused by the iterative interference cancellation is the main difficulty for the nonlinear detection to be put into practice.